Could you cite an example of any of such Tube amps (with 3D Holographic Soundstage) at 2/3rd of the Prelude's Street Price?
Any used ampsandsound amp on the classifieds, particularly the Forge (32/300 ohm) at 1500 used. It won't have the slam or macrodynamics of the OOR or even the Schiit Mjolnir 3, but it will stage like a concert hall with accurate 3D imaging with Susvara (provided you have a DAC capable of holographic imaging). You would have to go with Envy with Elrog Mo tubes if you want to get the dynamics along with the concert hall staging.